1. Field of the Invention
The present invention relates to a holder device for rotatably holding a rolled print medium which is a long print medium wound into a roll.
2. Description of Related Art
A print device is known in the art in which printing is performed on a rolled print medium while the print medium is being conveyed by conveyor means such as a platen roller. The print medium could have any of a plurality of different widths. A rolled-print-medium holder device for rotatably holding the rolled print medium at a predetermined position is provided within such a print device.
The interior of the rolled-print-medium holder device is configured of a plurality of divided members for rotatably holding the print medium, and the holder device is formed by fixing together those members while the print medium is held therein. In such a case, ultrasonic welding is commonly used as the fixing method. The ultrasonic welding is a method of using the vibration of sound waves to adhere a composite resin or the like, by which frictional heat is generated in the workpiece instantaneously by powerful vibrations, to ensure that the connecting surfaces of the workpiece melt and adhere together One method of such fixing by ultrasonic welding is described in Japanese patent-application No. 2004-30752, which discloses a tape cartridge in which the degree of flatness of the outer peripheral surface of a reel hub can be ensured and in which magnetic tape can be suitably wound. With this method, melted resin can be prevented from flowing out onto the outer peripheral surface of a reel hub by forming an indented shape around the periphery of a welding rib that is formed on a weld surface of an upper reel, then ensuring that melted resin from the welding rib that melts during the ultrasonic welding is captured by the indented shape.
In this manner, conventional welding by ultrasonic welding involves melting a welding rib and connecting confronting surfaces of the two members that are to be fixed together, to weld them. Schematic views of the welding construction of a rolled-print-medium holder device created by such ultrasonic welding method are shown in FIGS. 25A through 25C.
As shown in FIG. 25A, when an axial member 201 having a circular cylindrical shape is to be welded to a holder member 200 in the conventional rolled-print-medium holder device, first of all, the axial member 201 is inserted and fitted into a space portion 203 formed by a circular cylindrical wall 202 that is formed in the holder member 200, up until leading end portions of welding ribs 205 and 206 that are formed on a leading end surface 204 thereof come into contact with a weld surface 207 of the holder member 200, as shown in FIG. 25A.
As shown in FIG. 25B, ultrasonic vibrations are subsequently applied thereto with the components in this inserted state, so that the leading end portions of each of the welding ribs 205 and 206 touching the weld surface 207 are melted by frictional heat. When that happens, the welding ribs 205 and 206 melt gradually, starting from peak portions thereof, to form melted resin portions 208 and 209 (FIG. 25C), and the melted resin portions 208 and 209 will fill the gaps between the welding ribs 205 and 206 and the weld surface 207.
Subsequently, as shown in FIG. 25C, the welding ribs 205 and 206 are completely melted, and the leading end surface 204 and the weld surface 207 are welded by the melted resin portions 208 and 209.